A backplane of this kind is known from Siemens Catalog ST 70, pages 5/93 to 5/96, 2005 edition. The backplane is intended for a programmable controller and has slots into which functional units, e.g. functional units in the form of a CPU board, communication board, input/output board or other board or module suitable for the programmable controller, can be inserted. The programmable controller is designed for controlling a technical process and for solving control and automation tasks in the lower, medium and upper performance class. Which functional units and how many of these functional units are to be used is dependent on the automation task to be solved, functional units being used on a redundant basis as required. Should the programmable controller have to be extended in order e.g. to solve a more complex automation task, it is generally necessary to equip the programmable controller with new CPU and/or other intelligent functional module, to replace already inserted modules by more powerful ones and/or to provide the programmable controller with additional software functional modules. This procedure is expensive and prone to error. In addition, it is necessary for a large number of functional units to be held in store.